[AMPS] volts, Hertz

Steve Harrison steveh@fons.com
Mon, 6 Oct 97 14:31:57 EST5EDT

At 09:17 AM 10/6/97 +0008, you wrote:

>the basic rules i follow (i claim no originality here)
>1.  turn it off
>2. unplug it
>3. short it with a low value resistor, then with a wire (that's any 
>and all points in the circuit where electrical energy can be stored.)
>4. work on it.

There MUST be another step between 3 and 4:

3.5 Connect a solid shorting wire across the energy sources which are
potentially dangerous *WHEN THEY RECHARGE THEMSELVES*; because they WILL.

Everybody knows how both oil-filled and electrolytic caps both will recharge
theirselves, particularly the older ones with relatively high ESR. This
shock is potentially more dangerous because it is more prone to INJURE a
worker who is not expecting any shock. While the shock might not be
sufficient to stop your heart, it IS likely to be high enough to make you
jerk or jump back...right into something sharp or even more dangerous.

>if you *must* work on it "alive," apply the "1 hand in a pocket" 
>rule.  (work on it with one hand only.  the other hand is in a 
>pocket.  this way you don't provide a path across your thorax, where 
>your heart resides.)

This is also improper and extremely poor advice: one should NEVER, EVER have
occasion or need to "work" on a live circuit with the potential of killing
or maiming. (yes, I know..once in a very rare while, you just cannot avoid
something of the kind..).

I've found the absolute safest way to work on anything with the potential to
shock me is to first sit back and THINK about it. And THINK some more. THINK
about all the things that can happen should you make a mistake and brush or
touch something you shouldn't; and think of ways AROUND putting yourself
into that position. PLAN exactly what you are going to do, how you will
stick that test probe into the circuit, and how you can stand so that if
shocked, you will at least not be thrown into things that can hurt. If it
works out that your plan will not work, then stop and THINK about it some more.

9 times out of 10, I come up with another way to accomplish the same task
WITHOUT having to expose myself to a possibly fatal or maiming slip.

73, Steve Ko0U/1

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